1. Field of the Invention
This invention relates to a heating apparatus comprising a natural draft combustion system for heating fluids. More particularly, this invention relates to a heating apparatus for heating fluids used in cooking, such as a fryer in which cooking oil is the cooking medium.
2. Description of Prior Art
Conventional fluid heating apparatuses, such as fryers, employing natural draft combustion systems include a container or tank for containmnent of the fluid being heated, at least one combustion chamber or space in heat exchange relation with the container or tank and having a heat inlet and a combustion products outlet, and an inspirator-type burner for combustion of a fuel in said combustion space, generating heat for transfer into said fluid. Conventional fryers typically employ a plurality of combustion spaces, normally in the form of flame tubes or fire tubes, each of which has a corresponding burer for combustion of the fuel therein.
In conventional fryers, the buner for a corresponding combustion space or tube is located at the front of the fryer within a space defined by the front of the housing/controls area and the front wall of the fluid container, that is at the heat inlet to the tube. To optimize the heat exchange between the products of combustion resulting from combustion of the fuel provided by the burer to the tube and the fluid to be heated, the length of the tube, which constitutes the primary heat exchange means, is maximized, allowing enough space for a flue box, or combustion products outlet or exhaust, but resulting in a minimum amount of space for the burner.
Due to the minimal amount of space provided for the burner, natural draft fryer design has evolved whereby right angle burners (FIG. 1a) and in-shot burners (FIG. 1b) that fire in a horizontal direction are used. However, from an overall product design, neither of these configurations are particularly desirable.
In particular, the right angle burners intrude into the space below and in front of the fry tank, thereby making servicing difficult and eliminating valuable space that could be used by other fryer system elements, for example oil filters. Furthermore, the right angle geometry results in a complex manufacturing task because it is necessary that gas lines and manifolds be positioned far below the fluid container.
Horizontal in-shot burners are less than ideal due to the fact that their short length results in fryer designs with reduced fuel input (Btu/hr) per combustion space or tube in order to maintain a reasonable efficiency. This, in turn, results in in-shot burners having either lower input ratings for reasonable efficiency, lower efficiency for a typical fuel input, or more tubes to achieve the desired input and efficiency, thereby creating cleaning and manufacturing issues.